Subject: Re: Again: Booting a Vax-Server 3100 with NetBSD-1.4
To: Jason Thorpe <thorpej@nas.nasa.gov>
From: Johnny Billquist <bqt@Update.UU.SE>
List: port-vax
Date: 06/28/1999 20:38:29
On Wed, 23 Jun 1999, Jason Thorpe wrote:

> On Wed, 23 Jun 1999 10:16:27 +0100 (BST) 
>  Andrew Phillips <atp@mssl.ucl.ac.uk> wrote:
> 
>  > Johnny Billquist Wrote:
>  > >
>  > >Obscure note on the pdp-11: it's actually middle-endian. :-)
>  > >A 32-bit integer is stored as 3412.
>  > >(Using the FP-11 for 32-bit stuff)
>  > >
>  > 
>  >      There's not many machines that have an Endian type
>  >      defined specifically for them. 
> 
> Part of the PDP-11's weirdness here is the fact that you're talking
> about something larger than a wordsize.  Going strictly on wordsize,
> the PDP-11 is little endian (1,2).
> 
> However, for whatever reason, the most significant word of a longword
> was stored first in memory; I don't remember if that was a software
> convention, or a hardware thing.

It was hardware. The FP-11 stored data that way. But to make
things even more interesting, some software actually stored longwords as
1234, neccecetating a word swap before using the hardware.
(Don't remember the software offhand...)

	Johnny

Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt@update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol